Melt Crystallization as a means of concentrating DMSO-based reaction mixtures. An unusual feature of DMSO is its ability to freeze at a relatively high temperature (18.5°C). This can allow you to remove the bulk of the DMSO in the mixture by crystallizing it in a controlled fashion. The product-enriched DMSO remaining can then be physically separated, for further processing. Water has a dramatic effect on the freezing point of DMSO, it should be remembered. Water depresses the melting point of DMSO, making it impractical to concentrate product mixtures in this way when even a few weight percent of water are present.